This application relates to the commonly assigned U.S. Pat. No. 4,069,186 pertaining to latex paint containing solid plastic pigment particles, and the disclosure thereof is incorporated herein by reference.
Prior to plastic pigment latex paints as disclosed in U.S. Pat. No. 4,069,186, conventional high quality latex paint compositions contained opacifying pigments such as TiO.sub.2 and non-opacifying pigments such as inerts or extenders to produce high quality paint films which can be easily washed or scrubbed without ruining the paint film surface. The quality of prior art paint films ordinarily is inversely related to the surface porosity of the dried or cured paint film wherein non-porous film surfaces are desirable and porous film surfaces are avoided so as to maintain a continuous integral paint film surface substantially free of surface porosity and quite resistant to permanent surface deterioration. A standard parameter for identifying and formulating conventional latex paints is the pigment-volume-content (PVC) of the paint wherein PVC indicates the percent by volume of dry pigment non-film-forming solids present in the dried paint film. High quality prior art paints are compounded below critical PVC which is a maximum PVC before paint film integrity properties quickly diminish.
Commonly assigned U.S. Pat. No. 4,069,186 discloses an improved latex paint composition utilizing solid non-film-forming plastic particles in combination with opacifying pigments to provide a latex paint composition having a pigment-volume-content (PVC) greater than the critical-PVC to provide substantially improved opacified paint films at a wide range of PVC levels above the critical-PVC. The dried paint films have excellent high opacity coincident with high enamel holdout and low surface porosity to produce paint films that maintain excellent film integrity and remain resistant to surface deterioration as well as being easy to scrub.
It now has been found that very desirable paint films can be obtained from plastic pigment latex paint compositions having substantially high PVC's beyond 75% PVC and broadly between 75% and 85% PVC. The dried paint films are continuous non-cracking film which surprisingly maintain substantial film integrity properties such as dirt resistance, grime resistance, mar resistance, stain resistance, abrasion resistance, scrub resistance, and like film integrity properties. The high PVC plastic pigment paints are highly loaded with non-film-forming polymeric particles (plastic pigment) but do not contain non-opacifying extender or filler pigments whereby cracking and non-continuous film formation are avoided. Small particle acrylic binders appear to properly coalesce at a rate sufficiently slow as to avoid internal stresses and resulting cracking in the film. The particular coalescent and higher boiling point glycols control the binder coalescence and is speculated to sinter or otherwise promote a surface effect with plastic pigment to obtain continuous films at extraordinary high PVC's above 75% PVC. Accordingly, it has been found that a good quality plastic pigment latex paint can be compounded containing substantial levels of non-film-forming polymeric particles in combination with opacifying pigments and acrylic binders. The resulting dried paint film produces resilient continuous and crack-free paint film surfaces which surprisingly resist film surface deterioration in a manner comparable to conventional high quality latex paint films.
These and other advantages of this invention will become more apparent by referring to the Detailed Description of the Invention.